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1.
J Gen Virol ; 103(5)2022 05.
Article in English | MEDLINE | ID: covidwho-1831591

ABSTRACT

Infection with the porcine epidemic diarrhoea virus (PEDV) causes severe enteric disease in suckling piglets, causing massive economic losses in the swine industry worldwide. Tripartite motif-containing 56 (TRIM56) has been shown to augment type I IFN response, but whether it affects PEDV replication remains uncharacterized. Here we investigated the role of TRIM56 in Marc-145 cells during PEDV infection. We found that TRIM56 expression was upregulated in cells infected with PEDV. Overexpression of TRIM56 effectively reduced PEDV replication, while knockdown of TRIM56 resulted in increased viral replication. TRIM56 overexpression significantly increased the phosphorylation of IRF3 and NF-κB P65, and enhanced the IFN-ß antiviral response, while silencing TRIM56 did not affect IRF3 activation. TRIM56 overexpression increased the protein level of TRAF3, the component of the TLR3 pathway, thereby significantly activating downstream IRF3 and NF-κB signalling. We demonstrated that TRIM56 overexpression inhibited PEDV replication and upregulated expression of IFN-ß, IFN-stimulated genes (ISGs) and chemokines in a dose-dependent manner. Moreover, truncations of the RING domain, N-terminal domain or C-terminal portion on TRIM56 were unable to induce IFN-ß expression and failed to restrict PEDV replication. Together, our results suggested that TRIM56 was upregulated in Marc-145 cells in response to PEDV infection. Overexpression of TRIM56 inhibited PEDV replication by positively regulating the TLR3-mediated antiviral signalling pathway. These findings provide evidence that TRIM56 plays a positive role in the innate immune response during PEDV infection.


Subject(s)
Coronavirus Infections , Porcine epidemic diarrhea virus , Animals , Antiviral Agents , Interferon-beta/genetics , Interferon-beta/metabolism , NF-kappa B/genetics , NF-kappa B/metabolism , Swine , TNF Receptor-Associated Factor 3/genetics , TNF Receptor-Associated Factor 3/metabolism , Toll-Like Receptor 3/genetics , Toll-Like Receptor 3/metabolism , Virus Replication
2.
Int J Mol Sci ; 23(4)2022 Feb 11.
Article in English | MEDLINE | ID: covidwho-1715396

ABSTRACT

Interferon-ß (IFN-ß) is a pleiotropic cytokine secreted in response to various pathological conditions and is clinically used for therapy of multiple sclerosis. Its application for treatment of cancer, infections and pulmonary diseases is limited by incomplete understanding of regulatory mechanisms of its functioning. Recently, we reported that IFN-ß activity is affected by interactions with S100A1, S100A4, S100A6, and S100P proteins, which are members of the S100 protein family of multifunctional Ca2+-binding proteins possessing cytokine-like activities (Int J Mol Sci. 2020;21(24):9473). Here we show that IFN-ß interacts with one more representative of the S100 protein family, the S100B protein, involved in numerous oncological and neurological diseases. The use of chemical crosslinking, intrinsic fluorescence, and surface plasmon resonance spectroscopy revealed IFN-ß binding to Ca2+-loaded dimeric and monomeric forms of the S100B protein. Calcium depletion blocks the S100B-IFN-ß interaction. S100B monomerization increases its affinity to IFN-ß by 2.7 orders of magnitude (equilibrium dissociation constant of the complex reaches 47 pM). Crystal violet assay demonstrated that combined application of IFN-ß and S100B (5-25 nM) eliminates their inhibitory effects on MCF-7 cell viability. Bioinformatics analysis showed that the direct modulation of IFN-ß activity by the S100B protein described here could be relevant to progression of multiple oncological and neurological diseases.


Subject(s)
Interferon-beta/metabolism , S100 Calcium Binding Protein beta Subunit/metabolism , Animals , CHO Cells , Calcium/metabolism , Cell Line, Tumor , Cricetulus , Humans , MCF-7 Cells , Nervous System Diseases/metabolism , Protein Binding/physiology
3.
J Exp Med ; 218(9)2021 09 06.
Article in English | MEDLINE | ID: covidwho-1467276

ABSTRACT

The three classes of interferons (IFNs) share the ability to inhibit viral replication, activating cell transcriptional programs that regulate both innate and adaptive responses to viral and intracellular bacterial challenge. Due to their unique potency in regulating viral replication, and their association with numerous autoimmune diseases, the tightly orchestrated transcriptional regulation of IFNs has long been a subject of intense investigation. The protective role of early robust IFN responses in the context of infection with SARS-CoV-2 has further underscored the relevance of these pathways. In this viewpoint, rather than focusing on the downstream effects of IFN signaling (which have been extensively reviewed elsewhere), we will summarize the historical and current understanding of the stepwise assembly and function of factors that regulate IFNß enhancer activity (the "enhanceosome") and highlight opportunities for deeper understanding of the transcriptional control of the ifnb gene.


Subject(s)
Epigenesis, Genetic , Gene Expression Regulation , Host-Pathogen Interactions/physiology , Interferon-beta/genetics , CCAAT-Enhancer-Binding Proteins/genetics , CCAAT-Enhancer-Binding Proteins/metabolism , DNA Methylation , Enhancer Elements, Genetic , Host-Pathogen Interactions/genetics , Humans , Influenza A Virus, H5N1 Subtype/pathogenicity , Interferon-beta/metabolism , Promoter Regions, Genetic , SARS-CoV-2/pathogenicity , Transcription, Genetic , Ubiquitin-Protein Ligases/genetics , Ubiquitin-Protein Ligases/metabolism
4.
PLoS Pathog ; 17(8): e1009800, 2021 08.
Article in English | MEDLINE | ID: covidwho-1435629

ABSTRACT

Type I Interferons (IFN-Is) are a family of cytokines which play a major role in inhibiting viral infection. Resultantly, many viruses have evolved mechanisms in which to evade the IFN-I response. Here we tested the impact of expression of 27 different SARS-CoV-2 genes in relation to their effect on IFN production and activity using three independent experimental methods. We identified six gene products; NSP6, ORF6, ORF7b, NSP1, NSP5 and NSP15, which strongly (>10-fold) blocked MAVS-induced (but not TRIF-induced) IFNß production. Expression of the first three of these SARS-CoV-2 genes specifically blocked MAVS-induced IFNß-promoter activity, whereas all six genes induced a collapse in IFNß mRNA levels, corresponding with suppressed IFNß protein secretion. Five of these six genes furthermore suppressed MAVS-induced activation of IFNλs, however with no effect on IFNα or IFNγ production. In sharp contrast, SARS-CoV-2 infected cells remained extremely sensitive to anti-viral activity exerted by added IFN-Is. None of the SARS-CoV-2 genes were able to block IFN-I signaling, as demonstrated by robust activation of Interferon Stimulated Genes (ISGs) by added interferon. This, despite the reduced levels of STAT1 and phospho-STAT1, was likely caused by broad translation inhibition mediated by NSP1. Finally, we found that a truncated ORF7b variant that has arisen from a mutant SARS-CoV-2 strain harboring a 382-nucleotide deletion associating with mild disease (Δ382 strain identified in Singapore & Taiwan in 2020) lost its ability to suppress type I and type III IFN production. In summary, our findings support a multi-gene process in which SARS-CoV-2 blocks IFN-production, with ORF7b as a major player, presumably facilitating evasion of host detection during early infection. However, SARS-CoV-2 fails to suppress IFN-I signaling thus providing an opportunity to exploit IFN-Is as potential therapeutic antiviral drugs.


Subject(s)
Interferon-beta/metabolism , SARS-CoV-2/immunology , Viral Proteins/metabolism , Adaptor Proteins, Signal Transducing/metabolism , Adaptor Proteins, Vesicular Transport/metabolism , Animals , Chlorocebus aethiops , Eukaryotic Initiation Factor-2/metabolism , HEK293 Cells , Humans , Interferon-beta/genetics , Interferon-beta/pharmacology , SARS-CoV-2/drug effects , STAT1 Transcription Factor/metabolism , Vero Cells , Viral Proteins/genetics
5.
Viruses ; 13(1)2020 12 30.
Article in English | MEDLINE | ID: covidwho-1389523

ABSTRACT

SARS-CoV-2 is highly pathogenic in humans and poses a great threat to public health worldwide. Clinical data shows a disturbed type I interferon (IFN) response during the virus infection. In this study, we discovered that the nucleocapsid (N) protein of SARS-CoV-2 plays an important role in the inhibition of interferon beta (IFN-ß) production. N protein repressed IFN-ß production induced by poly(I:C) or upon Sendai virus (SeV) infection. We noted that N protein also suppressed IFN-ß production, induced by several signaling molecules downstream of the retinoic acid-inducible gene I (RIG-I) pathway, which is the crucial pattern recognition receptor (PRR) responsible for identifying RNA viruses. Moreover, our data demonstrated that N protein interacted with the RIG-I protein through the DExD/H domain, which has ATPase activity and plays an important role in the binding of immunostimulatory RNAs. These results suggested that SARS-CoV-2 N protein suppresses the IFN-ß response through targeting the initial step, potentially the cellular PRR-RNA-recognition step in the innate immune pathway. Therefore, we propose that the SARS-CoV-2 N protein represses IFN-ß production by interfering with RIG-I.


Subject(s)
COVID-19/immunology , DEAD Box Protein 58/metabolism , Interferon-beta/metabolism , Nucleocapsid Proteins/metabolism , SARS-CoV-2/metabolism , A549 Cells , Animals , DEAD Box Protein 58/genetics , HEK293 Cells , HeLa Cells , Host-Pathogen Interactions/immunology , Humans , Protein Interaction Domains and Motifs , Receptors, Immunologic , Signal Transduction
6.
Science ; 371(6536): 1374-1378, 2021 03 26.
Article in English | MEDLINE | ID: covidwho-1255508

ABSTRACT

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continually poses serious threats to global public health. The main protease (Mpro) of SARS-CoV-2 plays a central role in viral replication. We designed and synthesized 32 new bicycloproline-containing Mpro inhibitors derived from either boceprevir or telaprevir, both of which are approved antivirals. All compounds inhibited SARS-CoV-2 Mpro activity in vitro, with 50% inhibitory concentration values ranging from 7.6 to 748.5 nM. The cocrystal structure of Mpro in complex with MI-23, one of the most potent compounds, revealed its interaction mode. Two compounds (MI-09 and MI-30) showed excellent antiviral activity in cell-based assays. In a transgenic mouse model of SARS-CoV-2 infection, oral or intraperitoneal treatment with MI-09 or MI-30 significantly reduced lung viral loads and lung lesions. Both also displayed good pharmacokinetic properties and safety in rats.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Coronavirus 3C Proteases/antagonists & inhibitors , Protease Inhibitors/pharmacology , Animals , Antiviral Agents/chemistry , Antiviral Agents/therapeutic use , COVID-19/pathology , COVID-19/virology , Cell Line , Cell Survival/drug effects , Chemokine CXCL10/metabolism , Disease Models, Animal , Drug Design , Humans , Interferon-beta/metabolism , Lung/immunology , Lung/pathology , Lung/virology , Mice , Mice, Transgenic , Oligopeptides , Proline/analogs & derivatives , Protease Inhibitors/chemistry , Protease Inhibitors/therapeutic use , Protease Inhibitors/toxicity , Rats , Rats, Sprague-Dawley , Viral Load/drug effects , Virus Replication
7.
Front Immunol ; 12: 656700, 2021.
Article in English | MEDLINE | ID: covidwho-1211815

ABSTRACT

SARS-CoV-2, the novel coronavirus infection has consistently shown an association with neurological anomalies in patients, in addition to its usual respiratory distress syndrome. Multi-organ dysfunctions including neurological sequelae during COVID-19 persist even after declining viral load. We propose that SARS-CoV-2 gene product, Spike, is able to modify the host exosomal cargo, which gets transported to distant uninfected tissues and organs and can initiate a catastrophic immune cascade within Central Nervous System (CNS). SARS-CoV-2 Spike transfected cells release a significant amount of exosomes loaded with microRNAs such as miR-148a and miR-590. microRNAs gets internalized by human microglia and suppress target gene expression of USP33 (Ubiquitin Specific peptidase 33) and downstream IRF9 levels. Cellular levels of USP33 regulate the turnover time of IRF9 via deubiquitylation. Our results also demonstrate that absorption of modified exosomes effectively regulate the major pro-inflammatory gene expression profile of TNFα, NF-κB and IFN-ß. These results uncover a bystander pathway of SARS-CoV-2 mediated CNS damage through hyperactivation of human microglia. Our results also attempt to explain the extra-pulmonary dysfunctions observed in COVID-19 cases when active replication of virus is not supported. Since Spike gene and mRNAs have been extensively picked up for vaccine development; the knowledge of host immune response against spike gene and protein holds a great significance. Our study therefore provides novel and relevant insights regarding the impact of Spike gene on shuttling of host microRNAs via exosomes to trigger the neuroinflammation.


Subject(s)
COVID-19/metabolism , Exosomes/metabolism , Interferon-Stimulated Gene Factor 3, gamma Subunit/metabolism , MicroRNAs/metabolism , Microglia/metabolism , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Ubiquitin Thiolesterase/metabolism , COVID-19/genetics , COVID-19/physiopathology , COVID-19/virology , Cell Line , Central Nervous System/immunology , Central Nervous System/physiopathology , Central Nervous System/virology , Endopeptidases/metabolism , Exosomes/genetics , Exosomes/pathology , Humans , Inflammation/immunology , Inflammation/virology , Interferon-beta/metabolism , MicroRNAs/genetics , Microglia/pathology , NF-kappa B/metabolism , Protein Stability , Tumor Necrosis Factor-alpha/metabolism
8.
Cell Mol Immunol ; 18(4): 945-953, 2021 04.
Article in English | MEDLINE | ID: covidwho-1104474

ABSTRACT

SARS-CoV-2 is the pathogenic agent of COVID-19, which has evolved into a global pandemic. Compared with some other respiratory RNA viruses, SARS-CoV-2 is a poor inducer of type I interferon (IFN). Here, we report that SARS-CoV-2 nsp12, the viral RNA-dependent RNA polymerase (RdRp), suppresses host antiviral responses. SARS-CoV-2 nsp12 attenuated Sendai virus (SeV)- or poly(I:C)-induced IFN-ß promoter activation in a dose-dependent manner. It also inhibited IFN promoter activation triggered by RIG-I, MDA5, MAVS, and IRF3 overexpression. Nsp12 did not impair IRF3 phosphorylation but suppressed the nuclear translocation of IRF3. Mutational analyses suggested that this suppression was not dependent on the polymerase activity of nsp12. Given these findings, our study reveals that SARS-CoV-2 RdRp can antagonize host antiviral innate immunity and thus provides insights into viral pathogenesis.


Subject(s)
COVID-19/metabolism , Coronavirus RNA-Dependent RNA Polymerase/metabolism , Interferon Regulatory Factor-3/metabolism , Interferon Type I/metabolism , SARS-CoV-2/metabolism , Adaptor Proteins, Signal Transducing/genetics , Adaptor Proteins, Signal Transducing/metabolism , Cell Nucleus/metabolism , DEAD Box Protein 58/genetics , DEAD Box Protein 58/metabolism , Host-Pathogen Interactions/immunology , Humans , Immunity, Innate , Interferon Regulatory Factor-3/genetics , Interferon Type I/genetics , Interferon-Induced Helicase, IFIH1/genetics , Interferon-Induced Helicase, IFIH1/metabolism , Interferon-beta/genetics , Interferon-beta/metabolism , Mutation , Phosphorylation , Promoter Regions, Genetic , Receptors, Immunologic/genetics , Receptors, Immunologic/metabolism , SARS-CoV-2/enzymology , Sendai virus/metabolism
9.
PLoS Pathog ; 17(2): e1008690, 2021 02.
Article in English | MEDLINE | ID: covidwho-1105832

ABSTRACT

Cytoplasmic stress granules (SGs) are generally triggered by stress-induced translation arrest for storing mRNAs. Recently, it has been shown that SGs exert anti-viral functions due to their involvement in protein synthesis shut off and recruitment of innate immune signaling intermediates. The largest RNA viruses, coronaviruses, impose great threat to public safety and animal health; however, the significance of SGs in coronavirus infection is largely unknown. Infectious Bronchitis Virus (IBV) is the first identified coronavirus in 1930s and has been prevalent in poultry farm for many years. In this study, we provided evidence that IBV overcomes the host antiviral response by inhibiting SGs formation via the virus-encoded endoribonuclease nsp15. By immunofluorescence analysis, we observed that IBV infection not only did not trigger SGs formation in approximately 80% of the infected cells, but also impaired the formation of SGs triggered by heat shock, sodium arsenite, or NaCl stimuli. We further demonstrated that the intrinsic endoribonuclease activity of nsp15 was responsible for the interference of SGs formation. In fact, nsp15-defective recombinant IBV (rIBV-nsp15-H238A) greatly induced the formation of SGs, along with accumulation of dsRNA and activation of PKR, whereas wild type IBV failed to do so. Consequently, infection with rIBV-nsp15-H238A strongly triggered transcription of IFN-ß which in turn greatly affected rIBV-nsp15-H238A replication. Further analysis showed that SGs function as an antiviral hub, as demonstrated by the attenuated IRF3-IFN response and increased production of IBV in SG-defective cells. Additional evidence includes the aggregation of pattern recognition receptors (PRRs) and signaling intermediates to the IBV-induced SGs. Collectively, our data demonstrate that the endoribonuclease nsp15 of IBV interferes with the formation of antiviral hub SGs by regulating the accumulation of viral dsRNA and by antagonizing the activation of PKR, eventually ensuring productive virus replication. We further demonstrated that nsp15s from PEDV, TGEV, SARS-CoV, and SARS-CoV-2 harbor the conserved function to interfere with the formation of chemically-induced SGs. Thus, we speculate that coronaviruses employ similar nsp15-mediated mechanisms to antagonize the host anti-viral SGs formation to ensure efficient virus replication.


Subject(s)
COVID-19/virology , Cytoplasmic Granules/metabolism , Endoribonucleases/immunology , Endoribonucleases/metabolism , SARS-CoV-2/physiology , Viral Nonstructural Proteins/immunology , Viral Nonstructural Proteins/metabolism , COVID-19/metabolism , Cell Line , Coronavirus/immunology , Cytoplasmic Granules/immunology , Cytoplasmic Granules/virology , Humans , Interferon-beta/immunology , Interferon-beta/metabolism , SARS-CoV-2/metabolism , Signal Transduction , Virus Replication/physiology
10.
Cell Host Microbe ; 29(3): 489-502.e8, 2021 03 10.
Article in English | MEDLINE | ID: covidwho-1064930

ABSTRACT

The SARS-CoV-2 virus, the causative agent of COVID-19, is undergoing constant mutation. Here, we utilized an integrative approach combining epidemiology, virus genome sequencing, clinical phenotyping, and experimental validation to locate mutations of clinical importance. We identified 35 recurrent variants, some of which are associated with clinical phenotypes related to severity. One variant, containing a deletion in the Nsp1-coding region (Δ500-532), was found in more than 20% of our sequenced samples and associates with higher RT-PCR cycle thresholds and lower serum IFN-ß levels of infected patients. Deletion variants in this locus were found in 37 countries worldwide, and viruses isolated from clinical samples or engineered by reverse genetics with related deletions in Nsp1 also induce lower IFN-ß responses in infected Calu-3 cells. Taken together, our virologic surveillance characterizes recurrent genetic diversity and identified mutations in Nsp1 of biological and clinical importance, which collectively may aid molecular diagnostics and drug design.


Subject(s)
COVID-19/immunology , COVID-19/virology , Interferon Type I/immunology , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Viral Nonstructural Proteins/genetics , A549 Cells , Adolescent , Adult , Aged , Aged, 80 and over , Animals , Base Sequence , COVID-19/blood , Cell Line , Child , Child, Preschool , Chlorocebus aethiops , Female , Gene Deletion , Genomics , HEK293 Cells , Humans , Infant , Interferon Type I/blood , Interferon-beta/blood , Interferon-beta/metabolism , Male , Middle Aged , Molecular Epidemiology , Reverse Genetics , Vero Cells , Viral Nonstructural Proteins/immunology , Young Adult
11.
Virus Res ; 278: 197843, 2020 03.
Article in English | MEDLINE | ID: covidwho-833528

ABSTRACT

Swine acute diarrhea syndrome coronavirus (SADS-CoV), a newly emerging enteric coronavirus, is considered to be associated with swine acute diarrhea syndrome (SADS) which has caused significantly economic losses to the porcine industry. Interactions between SADS-CoV and the host innate immune response is unclear yet. In this study, we used IPEC-J2 cells as a model to explore potential evasion strategies employed by SADS-CoV. Our results showed that SADS-CoV infection failed to induce IFN-ß production, and inhibited poly (I:C) and Sendai virus (SeV)-triggered IFN-ß expression. SADS-CoV also blocked poly (I:C)-induced phosphorylation and nuclear translocation of IRF-3 and NF-κB. Furthermore, SADS-CoV did not interfere with the activity of IFN-ß promoter stimulated by IRF3, TBK1 and IKKε, but counteracted its activation induced by IPS-1 and RIG-I. Collectively, this study is the first investigation that shows interactions between SADS-CoV and the host innate immunity, which provides information of the molecular mechanisms underlying SASD-CoV infection.


Subject(s)
Alphacoronavirus/physiology , Coronavirus Infections/immunology , DEAD Box Protein 58/antagonists & inhibitors , Interferon-beta/antagonists & inhibitors , Active Transport, Cell Nucleus , Animals , Cell Line , Cell Nucleus/metabolism , Coronavirus Infections/virology , DEAD Box Protein 58/metabolism , Host-Pathogen Interactions/immunology , Immunity, Innate , Interferon Regulatory Factor-3/metabolism , Interferon-beta/genetics , Interferon-beta/metabolism , NF-kappa B/metabolism , Phosphorylation , Promoter Regions, Genetic , Signal Transduction , Swine
12.
Nat Commun ; 11(1): 3810, 2020 07 30.
Article in English | MEDLINE | ID: covidwho-690732

ABSTRACT

The pandemic of COVID-19 has posed an unprecedented threat to global public health. However, the interplay between the viral pathogen of COVID-19, SARS-CoV-2, and host innate immunity is poorly understood. Here we show that SARS-CoV-2 induces overt but delayed type-I interferon (IFN) responses. By screening 23 viral proteins, we find that SARS-CoV-2 NSP1, NSP3, NSP12, NSP13, NSP14, ORF3, ORF6 and M protein inhibit Sendai virus-induced IFN-ß promoter activation, whereas NSP2 and S protein exert opposite effects. Further analyses suggest that ORF6 inhibits both type I IFN production and downstream signaling, and that the C-terminus region of ORF6 is critical for its antagonistic effect. Finally, we find that IFN-ß treatment effectively blocks SARS-CoV-2 replication. In summary, our study shows that SARS-CoV-2 perturbs host innate immune response via both its structural and nonstructural proteins, and thus provides insights into the pathogenesis of SARS-CoV-2.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/virology , Immune Evasion , Interferon Type I/metabolism , Pneumonia, Viral/virology , Signal Transduction , Betacoronavirus/genetics , Betacoronavirus/immunology , Betacoronavirus/metabolism , COVID-19 , Cell Line , Coronavirus Infections/immunology , Humans , Immunity, Innate , Interferon-beta/genetics , Interferon-beta/metabolism , Interferon-beta/pharmacology , Mutation , Open Reading Frames , Pandemics , Pneumonia, Viral/immunology , Promoter Regions, Genetic , SARS-CoV-2 , Signal Transduction/drug effects , Viral Proteins/genetics , Viral Proteins/metabolism , Virus Replication/drug effects
13.
Science ; 369(6508): 1249-1255, 2020 09 04.
Article in English | MEDLINE | ID: covidwho-654484

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the current coronavirus disease 2019 (COVID-19) pandemic. A major virulence factor of SARS-CoVs is the nonstructural protein 1 (Nsp1), which suppresses host gene expression by ribosome association. Here, we show that Nsp1 from SARS-CoV-2 binds to the 40S ribosomal subunit, resulting in shutdown of messenger RNA (mRNA) translation both in vitro and in cells. Structural analysis by cryo-electron microscopy of in vitro-reconstituted Nsp1-40S and various native Nsp1-40S and -80S complexes revealed that the Nsp1 C terminus binds to and obstructs the mRNA entry tunnel. Thereby, Nsp1 effectively blocks retinoic acid-inducible gene I-dependent innate immune responses that would otherwise facilitate clearance of the infection. Thus, the structural characterization of the inhibitory mechanism of Nsp1 may aid structure-based drug design against SARS-CoV-2.


Subject(s)
Betacoronavirus/chemistry , Immune Evasion , Immunity, Innate , Protein Biosynthesis , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/metabolism , Betacoronavirus/immunology , Betacoronavirus/metabolism , Betacoronavirus/physiology , Binding Sites , COVID-19 , Coronavirus Infections/immunology , Coronavirus Infections/virology , Cryoelectron Microscopy , DEAD Box Protein 58/genetics , DEAD Box Protein 58/metabolism , Humans , Interferon-beta/genetics , Interferon-beta/metabolism , Models, Molecular , Pandemics , Pneumonia, Viral/immunology , Pneumonia, Viral/virology , Protein Binding , Protein Domains , Protein Interaction Domains and Motifs , Protein Structure, Secondary , RNA, Messenger/metabolism , Receptors, Immunologic , Ribosome Subunits, Small, Eukaryotic/chemistry , Ribosome Subunits, Small, Eukaryotic/metabolism , SARS-CoV-2
14.
Science ; 369(6504): 718-724, 2020 08 07.
Article in English | MEDLINE | ID: covidwho-641396

ABSTRACT

Coronavirus disease 2019 (COVID-19) is characterized by distinct patterns of disease progression that suggest diverse host immune responses. We performed an integrated immune analysis on a cohort of 50 COVID-19 patients with various disease severity. A distinct phenotype was observed in severe and critical patients, consisting of a highly impaired interferon (IFN) type I response (characterized by no IFN-ß and low IFN-α production and activity), which was associated with a persistent blood viral load and an exacerbated inflammatory response. Inflammation was partially driven by the transcriptional factor nuclear factor-κB and characterized by increased tumor necrosis factor-α and interleukin-6 production and signaling. These data suggest that type I IFN deficiency in the blood could be a hallmark of severe COVID-19 and provide a rationale for combined therapeutic approaches.


Subject(s)
Betacoronavirus/immunology , Coronavirus Infections/immunology , Interferon alpha-2/metabolism , Interferon-alpha/metabolism , Interferon-beta/metabolism , Pneumonia, Viral/immunology , Adult , Aged , Betacoronavirus/physiology , COVID-19 , Coronavirus Infections/virology , Critical Illness , Cross-Sectional Studies , Female , Gene Expression Profiling , Humans , Immunity, Innate , Inflammation , Interleukin-6/metabolism , Male , Middle Aged , NF-kappa B/metabolism , Pandemics , Pneumonia, Viral/virology , SARS-CoV-2 , Signal Transduction , T-Lymphocyte Subsets/immunology , Tumor Necrosis Factor-alpha/metabolism , Viral Load
15.
Science ; 369(6504): 712-717, 2020 08 07.
Article in English | MEDLINE | ID: covidwho-594812

ABSTRACT

Excessive cytokine signaling frequently exacerbates lung tissue damage during respiratory viral infection. Type I (IFN-α and IFN-ß) and III (IFN-λ) interferons are host-produced antiviral cytokines. Prolonged IFN-α and IFN-ß responses can lead to harmful proinflammatory effects, whereas IFN-λ mainly signals in epithelia, thereby inducing localized antiviral immunity. In this work, we show that IFN signaling interferes with lung repair during influenza recovery in mice, with IFN-λ driving these effects most potently. IFN-induced protein p53 directly reduces epithelial proliferation and differentiation, which increases disease severity and susceptibility to bacterial superinfections. Thus, excessive or prolonged IFN production aggravates viral infection by impairing lung epithelial regeneration. Timing and duration are therefore critical parameters of endogenous IFN action and should be considered carefully for IFN therapeutic strategies against viral infections such as influenza and coronavirus disease 2019 (COVID-19).


Subject(s)
Alveolar Epithelial Cells/pathology , Cytokines/metabolism , Interferon Type I/metabolism , Interferons/metabolism , Lung/pathology , Orthomyxoviridae Infections/immunology , Orthomyxoviridae Infections/pathology , Alveolar Epithelial Cells/immunology , Animals , Apoptosis , Bronchoalveolar Lavage Fluid/immunology , Cell Differentiation , Cell Proliferation , Cells, Cultured , Cytokines/administration & dosage , Cytokines/immunology , Female , Influenza A Virus, H3N2 Subtype , Interferon Type I/administration & dosage , Interferon Type I/pharmacology , Interferon-alpha/administration & dosage , Interferon-alpha/metabolism , Interferon-alpha/pharmacology , Interferon-beta/administration & dosage , Interferon-beta/metabolism , Interferon-beta/pharmacology , Interferons/administration & dosage , Interferons/pharmacology , Male , Mice , Orthomyxoviridae Infections/metabolism , Receptor, Interferon alpha-beta/genetics , Receptor, Interferon alpha-beta/metabolism , Receptors, Interferon/genetics , Receptors, Interferon/metabolism , Signal Transduction , Tumor Suppressor Protein p53/metabolism
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